1. Technical Field
This disclosure relates to an electronic document.
2. Description of the Related Art
Electronic documents, such as PDF documents and Word (registered trade mark) documents, are distributed through various networks to transmit information. Depending on the information content, it is desirable to maintain confidentiality or to avoid leakage (unauthorized disclosure) of some electronic documents.
In order to meet this requirement, in the related art, a password is provided for reading an electronic document, thereby preventing unauthorized reading. This is called “document reading protection function”. However, this function is still not enough.
FIG. 12A is a block diagram schematically illustrating an example of a network in the related art for distributing electronic documents having the document reading protection function.
As shown in FIG. 12A, from a transmission source, an electronic document 2, distribution destinations of which are not specified, is distributed over the unspecified distribution destinations, such as a company A, a company B, and others. Here, assume a third party company C is able to obtain the electronic document 2 from the company A or the company B; however, since there is no record in the transmission source indicating the electronic document 2 has been sent to the company C, it is not clear whether the company C has obtained the electronic document 2. In addition, even when it is known that the company C has obtained the electronic document 2, it difficult to determine where the company C obtained the electronic document 2. Similarly, when another competitive company obtains the electronic document 2, it difficult to determine where the other competitive company obtained the electronic document 2 among the company A, the company B, the company C, and other third parties.
FIG. 12B is a block diagram schematically illustrating an example of a modified network in the related art to overcome the above problem.
In this example, from the transmission source, the electronic document 2, distribution destinations of which are specified, is created for and distributed to each of the specified distribution destinations. For example, in a document having a specified distribution destination, a watermark specific to a distribution destination is printed; alternatively, a password is provided for a specific distribution destination. With such a document having a specified distribution destination, there is a consensus that the company A, which is a distribution destination, does not distribute the document to a third party, such as the company C. This rule constrains the distribution destinations. As a result, the company C has to request the transmission source for distribution of the document. Receiving the request from the company C, and when the transmission source decides to distribute the document to the company C, the transmission source creates the document specific to the company C.
In the example shown in FIG. 12B, since the electronic document has to be created for each of the distribution destinations on the side of the transmission source, the workload of document creation on the side of the transmission source is high. In addition, when there is a new distribution destination, for example, when the company C requests to obtain the document, it takes quite a long time before the company C can obtain the document. Further, when a competitive company illegally obtains the document, although it is possible to determine from where the competitive company obtained the document, the competitive company cam easily read contents of the document.
For example, Japanese Laid Open Patent Application No. 2005-141746 discloses a technique of security authentication in a server through a network, in which the authentication is performed by software.
Japanese Laid Open Patent Application No. 2003-6028 discloses a technique of authenticating an ID and a password by software, in which a document is scrambled (encrypted).
Japanese Laid Open Patent Application No. 2001-256190 discloses a technique of performing authentication of a server by email, in which authentication of an ID and a password is performed by software.